14 research outputs found
Tameness of the pseudovariety LS1
The notion of k-tameness of a pseudovariety was introduced by Almeida and Steinberg and is a strong property which implies decidability of pseudovarieties. In this paper we prove that the pseudovariety LSl, of local semilattices, is k-tame.This work was supported, in part, by FCT through the Centro de Matemática da Universidade do Minho, and by the FCT and POCTI approved project POCTI/32817/MAT/2000 which is comparticipated by the European Community Fund FEDER
Proceedings of the 26th International Symposium on Theoretical Aspects of Computer Science (STACS'09)
The Symposium on Theoretical Aspects of Computer Science (STACS) is held alternately in France and in Germany. The conference of February 26-28, 2009, held in Freiburg, is the 26th in this series. Previous meetings took place in Paris (1984), Saarbr¨ucken (1985), Orsay (1986), Passau (1987), Bordeaux (1988), Paderborn (1989), Rouen (1990), Hamburg (1991), Cachan (1992), W¨urzburg (1993), Caen (1994), M¨unchen (1995), Grenoble (1996), L¨ubeck (1997), Paris (1998), Trier (1999), Lille (2000), Dresden (2001), Antibes (2002), Berlin (2003), Montpellier (2004), Stuttgart (2005), Marseille (2006), Aachen (2007), and Bordeaux (2008). ..
Strongly locally testable semigroups with commuting idempotents and related languages
International audienceIf we consider words over the alphabet which is the set of all elements of a semigroup S, then such a word determines an element of S: the product of the letters of the word. S is strongly locally testable if whenever two words over the alphabet S have the same factors of a fixed length k, then the products of the letters of these words are equal. We had previously proved in [19] that the syntactic semigroup of a rational language L is strongly locally testable if and only if L is both locally and piecewise testable. We characterize in this paper the variety of strongly locally testable semigroups with commuting idempotents and, using the theory of implicit operations on a variety of semigroups, we derive an elementary combinatorial description of the related variety of languages
Strongly locally testable semigroups with commuting idempotents and related languages
If we consider words over the alphabet which is the set of all elements
of a semigroup S, then such a word determines an element of S:
the product of the letters of the word. S is strongly locally testable
if whenever two words over the
alphabet S have the same factors of a fixed length k,
then the products of the letters of these words are equal. We had previously proved
[19] that
the syntactic semigroup of a rational language L is strongly locally testable if and only if
L is both locally and piecewise testable.
We characterize in this paper the variety of strongly
locally testable semigroups with commuting idempotents and, using the theory of implicit operations on a
variety of semigroups,
we derive an elementary combinatorial description of the related variety of languages